Low contact resistivity at the 10−4 Ω cm2 level fabricated directly on n-type AlN

• Published in: Applied physics letters Vol. 125; no. 8
• Main Authors: Cao, Haicheng, Nong, Mingtao, Li, Jiaqiang, Tang, Xiao, Liu, Tingang, Liu, Zhiyuan, Sarkar, Biplab, Lai, Zhiping, Wu, Ying, Li, Xiaohang
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 19.08.2024
• Subjects: Aluminum nitride; Carrier density; Contact resistance; Electrical resistivity; Interlayers; Metallizing; Optoelectronic devices
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0215744

Ultrawide bandgap aluminum nitride (AlN) stands out as a highly attractive material for high-power electronics. However, AlN power devices face performance challenges due to high contact resistivity exceeding 10−1 Ω cm2. In this Letter, we demonstrate achieving a low contact resistivity at the 10−4 Ω cm2 level via refined metallization processes applied directly to n-AlN. The minimum contact resistivity reached 5.82 × 10−4 Ω cm2. Our analysis reveals that the low contact resistance primarily results from the stable TiAlTi/AlN interface, resilient even under rigorous annealing conditions, which beneficially forms a thin Al–Ti–N interlayer, promotes substantial nitrogen vacancies, enhances the net carrier density at the interface, and lowers the contact barrier. This work marks a significant milestone in realizing superior Ohmic contacts for n-type AlN, paving the way for more efficient power electronic and optoelectronic devices.